First introduced in 1995, the RDK-Series 4K Gifford-McMahon Cryocoolers are the most reliable and versatile systems available in the marketplace.
 

SHI’s 4K Gifford-McMahon Cryocoolers are recognized as the most reliable and versatile systems available in the marketplace.  They feature high cooling capacities, compact designs and are orientation-free.  Models like the RDK-408D2 are the standard for MRI and other superconducting magnets.  These 4K Cryocoolers can be found cooling a wide variety of analytical and experimental devices, and offer a very cost effective alternative to open-cycle liquid helium systems.